Bottles in the nature of milk bottles have heretofore been closed with friction fitted cardboard disks, crimped on aluminium foil caps and crimped on paper caps, none of which are tamper resistant.
Tamper resistant closures are known for plastic bottles. One such proposal is advanced in British Patent 1,038,327 and includes a latch ring, a cap and a hinge band disposed between the cap and latch ring. This closure is required to be assembled onto the neck of the bottle and is not readily adapted for use with existing milk bottles and milk bottling machinery.
German Patent 3911537 describes a tamper resistant closure which includes a latch ring and screw cap, with frangible tabs and a seal therebetween. The latch ring is provided with radially angled teeth which are intended to coact with teeth on the bottle neck, to permit the latch ring to rotate on the neck in a clockwise direction, but which precludes its rotation in an anticlockwise direction.
U.S. Pat. No. 4,394,918 describes a one piece tamper resistant closure for screw bottles which includes a latch ring with axially angled teeth and frangible tabs which bridge between the latch ring and screw cap, and a hinge which interconnects the latch ring and screw cap. When the cap is initially unscrewed, the latch ring will pivot about the hinge, and a considerable mechanical advantage will be generated which will assist in rupturing the frangible tabs.
Re-usable glass bottles such as milk bottles have traditionally used push on type closures, and it would involve a major capital cost to convert to screw type bottles. Moreover, it is impractical to provide in these types of bottles expedients such as ratcheting teeth. The diameter of the necks of these bottles is relatively large, and given the relatively wide tolerances to which the bottles are manufactured, it has been generally thought necessary to use some type of crimping operation to provide an adequate seal. Generally speaking, the closures of the prior art milk bottles have been of a type whereby they provide an inadequate re-closing function following their initial removal from the bottle.
It will be appreciated that where a tamper resistant feature of a push-on closure involves the use of frangible tabs, reliance cannot be made on the mechanical advantage provided by screw threads to generate a force that is adequate for their rupture.
Where the bottles to which the bottle caps are to be fitted are returnable for re-use, it is undesirable that the latch ring remains firmly attached to the bottle following the removal of the bottle cap.
It is a primary object of this invention to provide a one piece molded tamper resistant push-on closure that is suited for closing glass bottles.
It is another object of this invention to provide such closures which do not necessitate assembly on the neck of the bottle, and which accordingly, are readily adaptable for use with existing closure machinery.
It is yet another object of this invention to provide such closures with frangible members that can be ruptured without the necessity of using excessive force.
It is still a further object of this invention to provide such closures that are easily removable to permit the re-use of the bottle.
It is a still further object of this invention to provide closures of the above type that provide a good re-closure following their initial removal.